Question

I have this type of class hierarchy:

public interface IA{}

public interface IB{void Foo();}

public class A:IA
{
 [Dependency]
 IB myb{get;set;}

 void myfunc(){ myb.Foo()}
}

public class B:IB
{
 public B(IA ia){}
}

I want to make an instance of class A with Unity.
But when I want to make it I would want to write something like this:

public Testclass
{   
 void TestMethod()
 {
  IUnityContainer container = new UnityContainer();
  A currentA;
  container.RegisterType<IB,B>(new InjectionConstructor(currentA);
  currentA = container.Resolve<A>(); 
 }
}

This fails at the container.RegisterType line, saying that “Parameter type inference does not work for null values.”

How to make this work?

Edit: Ahhhh how I hate this… Our Architect made two interfaces with the same name, and that’s why I wasted 2 hours of my life. Daniel Hilgarth gave me a good idea, but I couldn’t use it until I realised that resharper imported the wrong interface.

Answer 1

You have a circular dependency. That’s bad. Either fix it or provide a factory for the creation of A.